linux-kernel - Re: [PATCH] ramoops appears geared to not support ARM

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Message-ID: <20111029093458.GX19187@n2100.arm.linux.org.uk>
Date:	Sat, 29 Oct 2011 10:34:58 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Marco Stornelli <marco.stornelli@...il.com>
Cc:	linux-arm-kernel@...ts.infradead.org, msb@...omium.org,
	linux-kernel@...r.kernel.org, sergiu@...omium.org,
	Bryan Freed <bfreed@...omium.org>, akpm@...ux-foundation.org,
	seiji.aguchi@....com
Subject: Re: [PATCH] ramoops appears geared to not support ARM

On Sat, Oct 29, 2011 at 10:39:47AM +0200, Marco Stornelli wrote:
> (Added linux-arm)
>
> Il 29/10/2011 01:21, Bryan Freed ha scritto:
>> I had some difficulty in getting ramoops to work on our ARM systems.
>> The driver maps memory with ioremap() which is supposed to map IO memory,
>> not physical RAM.  This happens to work on x86 and apparently some other
>> architectures, but it does not work on ARM.
>> Specifically, I see this comment in __arm_ioremap_pfn_caller():
>> 	Don't allow RAM to be mapped - this causes problems with ARMv6+
>>
>> So here is a patch that hacks around the issue using page_is_ram() to
>> differentiate between the two.
>>
>> Am I missing something here?
>> Is ramoops working on any ARM systems yet, and I am just doing something wrong?
>>
>> My ARM platform reserves a section of RAM for use by ramoops, but it is still
>> mapped along with the rest of main memory.  This is so /dev/mem can find it
>> with xlate_dev_mem_ptr().
>> On x86, I see our BIOS reserves the memory so that it is not counted as main
>> memory, and it is not mapped until ramoops ioremaps it.
>>
>> Bryan Freed (1):
>>    ramoops: Add support for ARM systems.
>>
>>   drivers/char/ramoops.c |   67 +++++++++++++++++++++++++++++++++++++----------
>>   1 files changed, 52 insertions(+), 15 deletions(-)
>>
>
> Can some ARM guys give an opinion about that?

Opinion about the patch which isn't present in this email (so we can't
see it) or about the commentry above?
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